Preparation of artificial filaments or threads



Dec. l, 1942A.

C. DREYFUS EVAL PREPARATION OF ARTIFICIAL FILAMENTS OR THREADS Filedsept. 21. 195s INVENTRS cAMlLLE DREYFUS GEORGE :SCHNEIDER ATTORNEYSPatented Dec. l, 1942 UNITED STATESA PREPARATION F ARTIFICIAL FILAMENTS0B THR EADS Camille Dreyfus, New York, N. Y., and George Schneider,Montclair, N. J., assignors to Celanese Corporation of America, acorporation of v Delaware Application September 21, 1939, Serial No.295,906 l 16 Claims. This inventionrelates to the production offilaments or threads from organic esters of cellulose,4

and relates more particularly to the preparation of such materials bythe extrusion of organic esters of cellulose while in molten state.

An 'object of our invention is to provide a method of preparingfilaments or threads from organic esters of cellulose which'is simplerand more expeditious than those formerly used.

A further object of our invention is to prepare filaments or threads.that are of greater tensile strength and of improved textile propertiesas compared with filaments or threads producedl from organic estersofcellulose by prior f 15 pipe I and may be melted by the heating mediumprocesses.

Other objects of our invention will appear from `the following detoueddescription. n Heretofore, in the production of filaments or threadsfrom organic esters of cellulose, either by the dryor evaporative methodor by the wet method of spinning, solutions of the organic esters ofcellulose in volatile organic solvents were extruded through theorifices of a spinneret into an evaporative coagulating medium. The uselof such volatile solvents, however, presents the disadvantages that itis costly to recoverI the same and even with the greatest care aconsiderable amount is lost, they are generally inflammable andtherefore present a fire risk, and some of the solvent is retained bythe yarns and filaf ments with the resultant effect on the tenacity andother properties of the same.

We have found that the disadvantages arising out of the use of volatilesolvents may be avoided l by shaping or extruding the organic ester ofcellulosevthrough the orifices of a spinneret while the same is inmolten condition. In this manner there are produced filaments or threadsthat are free of residual volatile solvent and therefore of superiortenacity and other textile properties.,

Further, we have found that if the solidified filaments or threads arestretched the resulting orientation of themat'erial produces increasedtenacity. l

In accordance with our invention melted or` ganic ester of cellulose ofgood stability is exlulose such as cellulosepropionate and cellulosebutyrate, or mixed esters suchas cellulose acetopropionate and celluloseaceto-butyrate- In the drawing, the figure shows one form of 5 apparatussuitable for Vcarrying out the invention,

this drawing being merely illustrative.

'Ihe apparatus comprises a closed vessel I provided with aremovablecover 2 anda jacket 3 for receiving a fluid heating medium, such assteam or hot Water which -may be` introduced through the pipe 5 andtaken off through pipe 4. The cellulose acetate, 6, can be introducedinto the vessel by removing the cover 2 or in the form of a slurryorsuspension through valved in the jacket.. Pressure may be built up inthe r inert liquid or gas under pressure introduced through pipe 8, thishot liquid or gas aidingin the melting of the cellulose acetate.4 Whenthecellulose acetate is melted it is forced, by means of the highpressure in the vessel I, through they valved outlet I0 into the headerI I and from the latter it is-delivered through pump I2 to`spinneret'sI3. The filaments I5 are (extruded through orices in the spinnerets intospinning cells or 'chambers I4 through which cool or cold air or othergas passes in order to set the formed filaments. The formed filamentsmay be collected on any suitable take-up means.`

By this invention filaments of low denier, say i from less than 2 to 10or more, which are associated together in required number to form yarn'-may be produced. -However, -laments of large denier, say from 150 to500 or more, which may be used as horsehair, bristles and the like, maybe made, as may be ribbons or bands to be used as articial straw. 'Ihemolten cellulose acetate may be extruded through metallic jets orspinv40 nerets of"sulicien't strength' and/or reinforced to withstandthe extrusion pressure, andfl which have orifices of required size, saycircular orifices of from 0.05 mm. in diameter or upward in the case ofmaking yarns or bristles, or the orifices may bein the frm of slits,when artificial straw is made. l'

Any `suitable temperatures and pressures may be employed for melting andextruding the cellulose acetate. We have found that although it isdiiiicult to melt cellulose acetate at ordinary pressures Withoutdecomposition, the cellulose'acetate canbe readilymelted'or at leastrendered suflil 5,5 air or otherlreactive gas. -Pressures of to 5 00 Avessel I by means of lsteam or hot water 9 or hot lbs. per squaretemperatures of For the same effect, the higher lower is the requiredtemperature.

We have found that the temperatures and pressures required formeltingand extruding the cellulose acetate may be reduced by heating thesame under pressure in the presence of water or other aqueous liquid, inwhich case the pressures employed to melt the cellulose acetate will befrom 50 to 250 or more pounds per square inch above atmospheric, and thetemperature will be that of boiling water at such pressures. Itispreferable to employ the higher pressures, i. e. 150 to 250 or morepounds per square inch and 150 C. upwards are employed.

inch are generally suitable and the pressure the the temperaturescorresponding thereto, i. e., i

about 185 to 210 C.

As an alternative and in some respects preferred method of lowering thetemperature required for melting, there is associated with the celluloseacetate relatively non-volatile solvents or plasticizers, in amounts offrom 10 to 50% or more of the cellulose acetate present. Examples ofsuch plasticizers are dimethyl phthalate, di-

Aethyl phthalate, dimethoxy ethyl phthalate, di-

butyl phthalate, triacetin, ethyl orthotoluene sulphonamide,ethyl'paratoluene sulphonamide. A mixture of two or more of theseplasticizers may be used. These plasticizers may be associated with thecellulose acetate in intimate admixture prior to melting in any suitablemanner, such as byl finely grinding the ingredients together; dissolvingthem in a volatile solvent to form a plastic mass, kneading the plasticmass under heat, and working the mass of heated malaxating rolls untilpractically all the volatile solvent is evaporated, etc.

The melting and extrusion of the cellulose acetate whether alone or inthe presence of water or plasticizer may be carried out in any suitableapparatus such as a closed vessel in which pressure may be exerted bymechanical means such as pistons, or .by hydraulic or pneumatic meanssuch as hot water, hot mineral oil or other inert liquid, or heatednitrogen, steam, carbon dioxide or other inert gas under pressure. Whenthe cellulose acetate is melted it is forced, by means of the high.pressure obtaining in the vessel, through a suitable opening in saidvessel into a header, and from the header the melted cellulose acetateis pumped into a spinneret from which the laments are extruded intosuitable orifices therein. A

In order to harden the filaments extruded from the spinnerets, they maybe extruded into a chamber through which cool or cold air or other gaspasses or into a cool or cold bath of water or other inert liquid. or ifspecial effects such as dyeing or saponiiication are desired into a bathcontaining the ingredients required to cause such effects, such asaqueous solutions of caustic soda or other alkali for saponication, oraqueous or other baths containing dyestuis or their components fordyeing. l

The filaments are then passed around godet rollers or other take-updevices which preferably rotate at a peripheral speed greater than thatat which the cellulose acetate is extruded so that the molten celluloseacetate filaments are drawn out as they leave the spinnerets, afterwhich they are. wound up, preferably with twisting. by a suitablemachinefsuch as a ring-spinning or captwisting'device when yarns l,aremade. However, in some instances, especially .when the yarns orfilaments are subsequently subjected to a stretchcase of artificialstraw or bristles, the plasticizer 'may be advantageously retained. l

ing operation, we prefer not to draw the filaments out, in which casethe godet rollers or other takeup devices are run at a peripheral speedequal to that at which the cellulose acetate is extruded.

We have found that if the filaments or yarns are drawn, and while theyare hard and at a temperature not substantially above room temperaturesand preferably below thesame, say from 0 to 30 C., the tenacity of thesame is greatly increased. The amount of stretching is on the` order of2O to 300% or more. This stretching may be done by passing the yarn orfilaments around rollers rotating atprogressively increasing peripheralspeeds or between the positive nip of pairs of rollers rotating atprogressively in. creasing peripheral speeds, and this stretching may beaccomplished in only one stage or in a multiplicity of stages.. lThecooling of the yarns or filaments for stretching may be accomplishedthrough the temperature of the surrounding atmosphere, but particularlygood results are obtained by rapidly cooling the yarns or fllamen... byimmersion in a relatively cold non-solvent such as water, which ifdesired may contain dyes, alkali for saponification, or other desiredsubstance.' This stretching operation may be carried out concomitantlywith the spinning operation, i. e., after the filaments are extruded andbefore they are wound onto packages; or as a separate operation, namelyafter the yarn has been formed and wound onto packages. If desired thestretching may be done on the yarns or filaments -While they containplasticizer. Alternatively the not for the cellulose acetate. In someinstanceswhere increased pliability is desired, as in the Any suitableeffect materials may be incorporated with the cellulose acetate prior tomelting and extrusion to obtain any desired effect. Thus, if yarns orfilaments of low luster are to be produced, -finely divided titaniumdioxide, antimony trioxide, etc., may be incorporated therein. Toproduce colored y-am, dyes, or finely divided pigments of organic 'orinorganic character as carbon black, graphite, ultramarine, may beincorporated.

It is to beunderstood .that the foregoingdetailed description is merelygiven by way of illustration and that many variations may be madetherein without departing from the spirit of our invention.`

Having described our invention, what we desire to secure by LettersPatent is:

1. Process for the production of filaments of organic esters ofcellulose, which comprises melting an organic. ester of cellulose undera pressure applied directly thereto by a hot aqueous liquid, extrudingthe molten organic ester of cellulose under suchpressure through oricesto form laments, andsetting said formed filaments.

2. Process for thev production of-illaments o'.' cellulose acetate,which comprises melting cellucellulose acetate, which comprises meltingcellulose acetate under a pressure applied directly thereto by a hotaqueous-liquid, extruding the molten cellulose acetate under suchpressure through orifices to form filaments, 'and setting said formedfilaments.

3. Process for vthe production of filaments of celluloseaceto-propionate', which comprises melting cellulose aceto-propionateunder a pressure applied directly thereto by a hot aqueous liquid,

' plied 'directly thereto by a. hot aqueous liquid, ex-

truding the molten cellulose aceto-butyrate under such pressure throughorifices to form filaments, and setting said formed filaments.

5. Process for the production of filaments. of organic esters ofcellulose, which comprises melting an organic ester of cellulose under apressure applied directly thereto by hot water, extruding the moltenorganic ester of cellulose under such pressure through orifices to formfilaments, and setting said formed filaments.

6. Process for the production of filaments of cellulose acetate, whichcomprises melting cellulose acetate under a pressure applied directlythereto by hot water, extruding the molten cellu- 'lose acetate undersuch pressure through orifices -to form filaments, and setting saidformed filaments.

'1. Process for the production of filaments of organic esters ofcellulose, which comprises melting an organic ester -of celluloseunder'a pressure applied directly thereto by a hot aqueous liquid,extruding the molten organic ester of cellulose under such pressurethrough orifices to form lalose acetate under a pressure applieddirectly thereto by hot water, extruding the molten cellulose acetateunder such pressure through orifices to form filaments, and cooling theformed fila- -ments atleast until they are solidified;

' thereto` by hot water, extruding the molten cellulose acetate undersuch pressure through orifices to form filaments, cooling the formedfilaments at least until they are solidied, and stretching saidfilaments.

13. Process vfor the production of laments of celluloseaceto-propionate, which comprises melting cellulose aceto-propionateunder a pressure applied directly thereto by hot water. extruding themolten celluloseV aceto-propionate under such pressure through orificesto form laments, cooling the formed filaments at least until they aresolidified, and stretching said filaments.

14. Process for the production of filaments of cellulose aceto-butyrate,which comprises melting cellulose aceto-butyrate under. a pressureapplied directly thereto by hot water. extruding the molten celluloseaceto-butyrate under such pressure through orificesto form filaments,cooling the formed filaments at least until they are solidified, andstretching said filaments.

15. Process for the production of filaments of organic esters ofcellulose, which comprises melting an organic ester of cellulose under apressure applied directly thereto by hot water, extruding the moltenorganic ester of cellulose under such pressure through orifices to formfilaments, coolorganic esters of cellulose, which comprisesmelting anorganic ester of cellulose under a pressure applied directly thereto byhot water, extruding the molten organic ester of cellulose under suchpressure through orices to form filaments, and cooling the formedfilaments at least until they are solidiiied.

10. Process for the production of laments of atleast until they aresolidied, and stretching said filaments in the presence of a coolingCAMILLE DREYFUS. GEORGE SCHNEIDER.

medium.`

